Investment Securities, Held to Maturity Securities, Transaction Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Investment Securities [Abstract]
Sales and transfers of held to maturity securities	$ 0	$ 0

For any transfer of securities categorized as held-to-maturity, this item represents the amount of the transferred security to another category of investments in debt and equity securities (trading or available-for-sale).

No definition available.

Name:	trst_HeldToMaturitySecuritiesSalesAndTransferredSecurity
Namespace Prefix:	trst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration